Tannin compounds

ABSTRACT

The invention herein disclosed provides a tannin especially effective as antipsychotic drug for mental disorders such as acute and chronic schizophrenia. This tannin composition is represented by the following general formula: ##STR1## wherein l is an integer from 0 to 6, m is 0 or 1, n is an integer from 0 to 6, l+n+m=6; 
     R 1  is hydrogen or G, G representing the galloyl group ##STR2## X is ##STR3## R 2  is OH, . . . OG, or . . . OH; filled dots mean bonding sites, there being no possibility to bond between the mutual fourth positions in each unit; there is only one bonding between the fourth and the sixth position; and there is a total of three galloyl groups in the tannin.

TECHNICAL FIELD

The present invention pertains to a novel tannin composition and, moreparticularly, to a novel tannin composition used for treating mentaldisorders such as acute and chronic schizophrenia and the like.

BACKGROUND ART

Rhei Rhizoma is a kind of crude drug previously known, and usedfrequently in traditional chinese prescription (Kampo). The Rhei Rhizomais so far known to possess an antibacterial effect, blood ureanitrogen-decreasing activity and anti-inflammatory effect. In the priorart, in order to obtain substances providing such effects, variouscompositions and/or compounds such as sennoside A have been isolatedfrom Rhei Rhizoma. However, among the compounds isolated from RheiRhizoma, no components usable for treating mental disorders have beenpreviously known at all.

Whereas, the following chemical compounds have been known asantipsychotic drugs used for treating schizophrenia:

Levomepromazine, chlorpromazine and thioridazine showing strong sedativeeffect; perphenazine, fluphenazine and haloperidol showing stronganti-hallucination and -delution effects; and sulpiride having mildsedative effect, and anti-hallucination and -delution effects. Thesedrugs have been selectively used, according to their respectivecharacteristics, in response to patient's symptoms and the progress ofdisease. However, it has been well-known that these drugs produceadverse effects which are extrapyramidal syndrome such as musclerigidity, dyskinesia and parkinsonism, and autonomic symptoms such assalivation, dry mouth and constipation. Consequently, a drug withoutadverse effects for treating mental disorders has long been desired tobe developed.

DISCLOSURE OF INVENTION

Therefore, one of the objects of the present invention is to provide anovel tannin composition.

Another object of the present invention is to provide a novel tannincomposition extracted from Rhei Rhizoma.

A further object of the present invention is to provide such noveltannin composition having a potent antipsychotic effect, which can beused for treating acute and chronic schizophrenia, without causing anyadverse effects.

These and other objects, together with the advantages thereof over theprior art, will become apparent from the following description and theappended claims.

A tannin according to the present invention is represented by thefollowing general octameric structural formula: ##STR4## wherein

1 is an integer from 0 to 6, m is 0 or 1, n is an integer from 0 to 6,and l+m+n=6;

R₁ is hydrogen or G, G representing galloyl group ##STR5##

X is ##STR6##

R₂ is OH, . . . OG, or . . . OH; and filled dots mean bonding sites, andthere is no possibly to bond between the mutual fourth positions in eachunit, and there is only one bonding between the fourth position and thesixth position; and there is a total of three galloyl groups in thetannin.

In accordance with the present invention, the above tannin compositionmay be obtained by the following steps:

obtaining an extractive from Rhei Rhizoma with water or an aqueoussolution of an organic solvent;

separating said extractive or its concentrated liquid by gel filtrationchromatography using water, an aqueous solution of ethanol, ethanol andmethanol sequentially, to obtain a methanolic eluate;

separating said methanolic eluate, its concentrated liquid or driedsolid by gel filtration chromatography with a mixture of at least twosolvents selected from the group consisting of water, ethanol, methanoland acetone, to obtain an eluate;

subjecting said eluate to high performance liquid chromatography[column: Nucleosil 5C₁₈ (Macherey-Nagel) (4×250 mm); mobile phase:14-80% CH₃ CN/H₂ O (25 mM oxalic acid); flow rate: 1 ml/min; columntemperature: 40° C.], to separate and obtain a fraction eluted at theretention time from 10 to 25 minutes; and

removing the solvent from said eluted fraction.

It is also disclosed, according to the present invention, that the abovetannin composition is effective in treating mental disorders such asacute and chronic schizophrenia.

BEST MODE FOR CARRYING OUT THE INVENTION

Rhei Rhizoma used in order to obtain a novel tannin compositionaccording to the present invention is commercially available in the formof crude drugs. The original plant of Rhei Rhizoma is a perennial herbbelonging to the Polygonaceae family.

Rhei Rhizoma is first extracted by using water or an aqueous solution ofan organic solvent, in order to obtain a desired extractive. Thisextraction process is carried out at the temperature ranging from roomtemperature to the boiling point of the extracting solvent to be used.Preferably Rhei Rhizoma may be previously reduced to powders, and inthis case high extracting efficiency is achieved. Ethanol, methanol,acetone and etc. are preferable as an extracting organic solvent. It ismost recommendable to extract using water for 12 through 24 hours atroom temperature. In this manner, the resultant extractive contains aminimum of contaminants other than the desired tannin composition ofthis invention. Repeating the above extraction process 2 through 4 timesbrings higher extracting efficiency.

The extractive obtained in the above extracting process may be directlysubjected to gel filtration chromatography. Alternatively, theextractive may be concentrated prior to being subjected to thechromatography. Preferable examples of gel used in the gel filtrationchromatography are Sephadex® (Pharmacia Fine Chemicals), MCI gel®(Mitsubishi Kasei) and μ-Bondapak® (Waters Associates). Water, anaqueous solution of ethanol, ethanol and methanol are sequentiallyemployed as eluting solvents. In case where MCI gel® or μ-Bondapak® isused, methanol may be introduced immediately after water introduction.By this procedure, a methanol eluate is obtained.

The methanol eluate obtained in the above eluting process, itsconcentrated liquid or dried solid is subjected to gel filtrationchromatography. An eluate is obtained in the chromatography by using amixture of at least two solvents selected from the group consisting ofwater, ethanol, methanol and acetone. Preferable examples of packinggels employed are Sephadex® (Pharmacia Fine Chemicals), MCI gel®(Mitsubishi Kasei) and μ-Bondapak® (Waters Associates). In case whereSephadex® is used as a packing gel, a mixture of ethanol, water andacetone is the most suitable solvent. In case where MCI gel® is packedin the column, a mixture of ethanol-water or methanol-water is the mostsuitable solvent. In this manner, a desired eluate is obtained.

The eluate obtained in the preceding process is subjected, as it is, tohigh performance liquid chromatography [column: Nucleosil 5C₁₈(Macherey-Nagel) (4×250 mm); mobile phase: 14-80% CH₃ CN/H₂ O (25 mMoxalic acid); flow rate: 1 ml/min; column temperature: 40° C.].

And then a fraction eluted at the retention time from 10 to 25 minutesis separated to obtain a desired eluted fraction.

Lastly, the eluting solvent is removed by evaporation at reducedpressure from the fraction eluted in the preceding process, resulting inthe separation of tannin composition according to the present invention.

Preferably examples of the pumps used in the above high performanceliquid chromatography are TOYOSODA CCPD Dual Pump (Toyosoda Kogyo),Waters 6000A-type Pump (Waters Associates), JASCO TRI ROTAR-VI Pump(Nihon Bunko Kogyo), Hitachi 655-type Pump (Hitachi Seisakusho), etc. Inaddition, preferable examples of the detectors used in the highperformance liquid chromatography are TOYOSODA UV-8 Model II (ToyosodaKogyo), Waters Model 440 Absorbance-detector (Waters Associates), JASCOUVIDEC-100-VI UV Spectrometer (Nihon Bunko Kogyo), Hitachi 638-41-typeVariable-wavelength UV Monitor (Hitachi Seisakusho), etc. A suitableabsorption wavelength in the detection is 280 mm. A more detailedexplanation regarding preparation of the tannin composition of thepresent invention is provided with the example hereinbelow.

EXAMPLE

Powdered Rhei Rhizoma (3 kg) was steeped in purified water (15-25liters), and extracted at room temperature for 12-24 hours. The sameextraction process was repeated three times to produce three sameextractives. The combined extractives were concentrated to 4 liters atreduced pressure. This concentrate was subjected to columnchromatography [Sephadex® LH-20 (Pharmacia Fine Chemicals 25-100micrometers), (11×50 cm)]. The column was eluted using water,water-ethanol (1:1), ethanol, methanol, aceton-water (1:1) (20 literseach) sequentially, and each fraction was obtained. The yields of thesefour fractions were 525, 193, 67, 47 grams, respectively.

The fraction No. 4 (36 grams) was subjected to column chromatography[Sephadex® LH-20, (5.8×50 cm)], and the column was eluted with a mixtureof ethanol-water-aceton (1:0:0, 19:0.5:0.5, 18:1:1, 17:1.5:1.5, 16:2:2,15:2.5:2.5, 14:3:3, 13:3.5:3.5, 12:4:4, 11:4.5:4.5, 10:5:5, 8:6:6,0:1:1, 4 liters each). The eluate liquid was subjected to a highperformance chromatography [pump: TOYOSODA CCPD Dual Pump; detector:TOYO SODA UV-8 Model II; column: Nucleosil 5C₁₈ (Macherey-Nagel) (4×250mm); mobile phase: 14-80% CH₃ CN/H₂ O (25 mM oxalic acid); flow rate: 1millimeter/min; column temperature: 40° C.; absorption: 280 nm]. Thefraction eluted at the retention time from 10 to 25 minutes wasseparated. The solvent was removed from the separated fraction byevaporation and 15.6 grams of the tannin composition of the presentinvention, was finally obtained.

Pharmacological Assessment

The test substance was dissolved in saline (0.9% NaCl) and administeredi.p. or p.o. to rats in a single-dose study. To control group, onlysalines (i.p.) or water (p.o.) was administered.

EXAMPLE 1

Eight male SD rats, 5-6 weeks of age, were used for each i.p. dose (0,5, 10, 20 and 50 mg/kg).

In the open field test, the test substance reduced the locomotoractivity and rearing dose-dependently.

These suggest that the test substance has sedative effect.

EXAMPLE 2

Eight male SD rats, 5-6 weeks of age, were used for each i.p. dose (0, 1and 2 mg/kg). The test substance was administered 1 hour prior tod-methamphetamine (1 mg/kg, s.c.). d-Methamphetamine is known to produceabnormal behavioral in animals. The test substance at 1 and 2 mg/kginhibited d-methamphetamine-induced locomotor hyperactivity. (Graphs 1Aand 1B)

Therefore, it is clearly indicated that the test substance hasanti-methamphetamine effect. This inhibitory effect is twice as potentas chlorpromazine. ##STR7##

EXAMPLE 3

Ten male Wistar-King A rats for each group, 5-6 weeks of age, were used.The olfactory bulbs of these rats were removed (O.B. rats), whichresulted in the appearance of aggressive behavior. The effects of thetest substance on agressive behavior induced by olfactory bulbectomywere evaluated by the following 6 parameters;

1. attack: attack response to a rod presented in front of the snout.

2. tapping: jumping or startle response to tapping on the back

3. pinching: flight response or attack response to tail pinching.

4. capture: struggle response to capturing.

5. vocal: vocalization during the observation period.

6. muricide: mouse killing behavior.

These parameters were graded on a 0-4 basis (score 0: no response--score4: maximal response). The total score was made by summing up each scoreof 6 parameters. The test substance i.p. administered at 1, 2 and 5mg/kg significantly lowered total score of aggressive behaviors (Graph2). This effect continued for up to about 6 hours. The test substanceorally administered at 10 and 20 mg/kg showed similar inhibitory effectsto the above by i.p. administration.

These results suggest that the test substance has anti-aggressiveeffect.

This inhibitory effect is 10 times as strong as haloperidol and twich asstrong as chlorpromazine.

During the above 3 experiments, catalepsy, ataxia and muscle relaxationwere not observed. ##STR8##

Toxicological Assessment

LD₅₀ of the test substance in mice is as follows. The test substance wasdissolved in saline except for oral administration (in water).

    ______________________________________                                        Animal: ddY male mice (n = 10), 4 weeks of age.                               Route of administration                                                                          LD.sub.50 (mg/kg)                                          ______________________________________                                        intravenously administration                                                                      70.9                                                      intraperitoneal administration                                                                   369.4                                                      oral administration                                                                              >1000                                                      subcutaneous administration                                                                      >1000                                                      ______________________________________                                    

The overall results obtained indicate the possibility that the testsubstance may be useful for some psychiatric disorders in human.

Practical Use

Medicines in the wide variety forms such as liquid, powder, granulatedpowder, pill, tablet, enteric coated tablet and capsule may be producedin the conventional manner by using this tannin composition togetherwith suitable solvent, excipient, adjuvant, etc. The above medicines maybe compounded into other medicinal active ingredient in case ofprescribing. For oral administration, medicines in the form of liquid,powder, granulated powder, pill, tablet, enteric coated tablet andcapsule may be prescribed by using at least one excipient such asstarch, lactose, sucrose, mannitol and carboxymethylcellulose. The abovemedicines may also be produced by using brighteners such as magnesiumstearic acid, sodium lauric acid and talc; binders such as dextrin,crystalline cellulose, polyvinyl pyrrolidone and gelatin; and breakingagents such as potato starch and carboxymethylcellulose. This tannincomposition may be administered as suspension, emulsion, syrup andelixior, which may contain taste and odor correcting agent and coloringagent.

In case of production of injecting medicines, there may be used diluentssuch as an injecting vegetable oil, propylene glycol and polyethyleneglycol. Further, isotonic agents, stabilizer, antiseptics and anodynesmay be added if necessary. It is preferable to dissolve the injectingmedicines in a sterilized injecting medium. All percentage and ratiosstated herein are by volume unless otherwise expressly indicated.

I claim:
 1. A tannin represented by the following general octamericstructural formula: ##STR9## wherein 1is an integer from 0 to 6, m is 0or 1, n is an integer from 0 to 6, and l+m+n=6;R₁ is hydrogen or G, Grepresenting galloyl group ##STR10## X is ##STR11## R₂ is OH, . . . OG,or . . . OH; and filled dots mean bonding sites, and there is nopossibility to bond between the mutual fourth positions in each unit,and there is only one bonding between the fourth position and the sixthposition; there being a total of three galloyl groups in the tannin.